We must not shrink for want of courage when it is needful to unveil facts of the spiritual world entering deep into the life of man. For the whole future of mankind depends on man’s learning really to live with the spiritual world as naturally as on the Earth he lives with the physical. Mankind must learn to be at home again in the spiritual world as it was in the beginning, in primeval time. Only by doing so shall we be helping mankind’s future. In the true sense we must understand the word of Christ: “My Kingdom is not of this world”.
Source: Rudolf Steiner- GA 218 – Man’s Life on Earth and in the Spiritual Worlds : LECTURE VI – London, 19th November 1922
Translated from the German by George and Mary Adams
The great Rudolf Steiner Quotes Site 